The application of a laser Doppler velocimetry system to flow velocity measurements in a transonic compressor.

Abstract

A laser doppler velocimeter (LDV) system was developed and utilized to measure the flow velocities in the axial and tangential directions behind the rotors of a single stage transonic compressor. The backscatter mode was used to acquire the scattered light signals from particles that were seeded into the airflow upstream of the compressor. The light signals were generated as the particles traversed a fringe pattern produced by the intersection of two laser beams. The LDV system proved that it was possible to make velocity measurements in the transonic compressor. The results revealed a variation of the flow velocity in both the axial and tangential directions due to the formation of a wake caused by the passage of rotor blades. The velocity measurements were comparable to those acquired through pressure probe measurements.